DIFFERENT WEIGHT / BRAND BRASS 7mm.RM

[wheelgunner]

Hello guys,

last week i was at the shooting range to try some reloads for my Tikka T3 (... not the lite model ...) 7mm.RM.

I was to the "second turn" of shooting for the Hirtemberger brass, and the loads i was trying is:

Nosler Ballistic-Tip 150 grs.
IMR7828 x 68.00 grs.
Federal GM215M
Lenght: 83.00 mm. (the FB=0 is at a lenght of 85.20)

The brass, after the first turn of shoot, was FL sized by RCBS Competition die, trimmed at 63.30 mm. and deburred.

The very strange thing is the weight of theese brass: 265 grs. (+/- 0.4 grs.), compared with my Norma brass (220 grs.) ..... i can't believe a different of 45 grains ! .....

The recoil was very strong, with a very big flash, over the muzzle of the barrel.
I made the better group (3 shot) in 0.6 inch (16 mm.) at 200 mt. .... but watching the spent primers, they was a little bit "planed" (excuse me i don't know the right word in english), but not craterized.
Ok, it's a sign of high pressure, but the spent brass was coming out smooth from the bolt .....

My question is: maybe the IMR7828 it's too much progressive for my barrel lenght ? (24 inches), and the 68.00 grs. are (maybe) too much in theese brand of brass, so heavy and (i think) with less internal capacity ?

I would be really sorry to don't use this load, because it's very accurate .... i would like to try using the Norma Brass

 

[jmason]

According to QuickLoad you are right at max charge. Some of the flash maybe due to all the powder not burning up in your barrel. Quickload also says with the 24" barrel about 1.5% of you powder isn't burning until after the bullet exits the barrel. It has been stated before that brass can change things. All you can do is try and see. Keep us posted.

Hopefully this info is somewhat useful.

 

[wheelgunner]

According to QuickLoad you are right at max charge. Some of the flash maybe due to all the powder not burning up in your barrel. Quickload also says with the 24" barrel about 1.5% of you powder isn't burning until after the bullet exits the barrel. It has been stated before that brass can change things. All you can do is try and see. Keep us posted.

Hopefully this info is somewhat useful.

Thank you for your reply, i'll take two ways:

- reduce the IMR7828 (in Hirtemberger brass) about 66.00 and 67.00 grs.
- try to load the IMR7828, in Norma brass, at 67.00 and 68.00

i'll let you know !